TM 5-3895-374-24-2
AUXILIARY VALVE ADJUSTMENT
The
auxiliary
valve
is
mounted
on
the
bare
compressor. The valve has a cut-out and a differential
adjustment. The cut-out point is the pressure at which the
valve will open allowing the compressor to unload, the cut-in
point is the pressure at which the valve will close allowing the
compressor to reload, and the differential is the span between
the cut-out and the cut-in points.
Figure 3-3.Typical Auxiliary Valve adjustments.
To adjust the cut-out pressure, (See Figure 3-3,)
loosen the range locknut and turn the range adjustment screw
clockwise for higher pressure and counterclockwise for lower
pressure. Retighten the range locknut after adjusting the cut-
out pressure.
The differential pressure will vary with the change in
cut-out pressure.
The differential pressure is preset at approximately
15% of the cut-out pressure and should not be re-adjusted
unless absolutely necessary. Small differentials, 5 PSIG or
less, tends to produce internal chattering and should be
avoided.
To adjust the differential pressure, (See Figure 3-3),
loosen the differential locknut and turn the differential nut
clockwise for greater differential and counterclockwise for less
differential.
While adjusting the differential nut, the range locknut
should be loosened and the range adjustment screw must be
held from turning to avoid changing the cut-out
pressure.
Retighten the differential locknut and the range locknut after
adjusting the differential pressure.
INTERMITTENT DUTY FORMULA
Model 7100 operating above 200 psig (14 kg/sq.
cm) are to be operated according to the "Intermittent Duty
Formula."
INTERMITTENT DUTY FORMULA
Pump-up time should not ordinarily exceed thirty (30)
minutes or be less than ten (10) minutes. Shutdown
periods between cycles of operation should be at least
equal to the pump-up time. Note: When the compressor
is regulated by constant speed control, the shut-down
period is the time the compressor is operating unloaded.
A pump-up time limit with the following cool-down
period is recommended to protect the valves and heads
against stabilized high operating temperatures, which could
rapidly build up carbon in these areas.
All inquiries for high-pressure compressor application
where the "use" cycle differs from the "Intermittent Duty
Formula" should be referred to the nearest Ingersoll-Rand
branch office.
page 3 - 835
